Many languages associate the t
sound with the second person and the s
with the third. For example Spanish (tu/tuyo, su/suyo), French (tu,ton/ta/tes,son/sa/ses), Italian (tu,tuo/tua/tuoi,suo/sua/suoi) etc. Even English associates t with the second person (thy,thine etc). German does not seem to have t for the second person (though it has d which is close) but does have third person adjectives beginning with s (sein/seine).
Modern (and I would guess Ancient as well) Greek, however has the inverse.
The second person is associated with the s
sound and the third with t
. Σου, pronounced su just like in Spanish means your(s) and του, again pronounced exactly like the Spanish tu, means his. I can imagine that του may have originated from the word for self (ἑαυτού/τον/τος) but, in that case, why the third person?
So, my question is about the history and origin of this association between s
and t
and the third and second person respectively. Is it a characteristic of Proto-Indo-European and, if so, what happened to Greek? Did PIE have such adjectives and, if so, did they also start with t
and/or s
? Any extra historical information on the origin and phylogeny of these possessives would also be very welcome.